Electrodynamic compressor



Oct. 7, 1941. E. F. .SARVER 2,257,862

ELECTRODYNAMIC C OMPRES SOR Filed Nov. 8, 1937 v 2 Sheets-Sheet l INVENTOR A O Y Oct. 7, 1941. E. F. SARVER 2,257,862

ELECTRODYNAMIC COMPRESSOR Filed NOV. 8, 1937 2 Sheets-Sheet 2 ENTOR F Sam/er.

Patented Oct. 7, 194.1

ELECTBODYNAMIC COMPRESSOR Emmett F. Sal-yer, HaysQKans alignor to General Motors Corporation, Dayton, Ohio, a eor-' notation of Delaware Application November 8, 1931, Serial No. masts 3 Claims. (Cl. 230-55) This invention relates to compressors and particularly to those for compressing gaseous fluids such as used in refrigeration systems and the like.

The principal objects of the invention are to provide an electrodynamic compressor that is of simple and inexpensive construction; to provide a compressor of this character which does not require lubrication; to provide a compressor that is compact and adapted to be completely sealed in a gas-tight housing; to provide a compressor that is quiet in operation; and to provide a compressor that will function successfully though the voltage of the current supply fluctuates widely.

In accomplishing these and other objects of the invention, as hereinafter pointed out, I have provided improved details of structure, the prei'erred form of which is illustrated in the accompanying drawings, wherein:

Fig. 1 1s a longitudinal section through an electrodynamic compressor constructed in accordance with the present invention.

Fig. 2 is"a,cross-section through the compressor on the line 2-2 of Fig. 1.

Fig. 3 is a cross-section on the line 2-2 of Fig. 1.

Fig. 4 is a cross-section through one of the bevels on the line 4-4 of Fig. 1.

Referring more in detail to the drawings: 1

I designates a compressor constructed in accordance with the present invention and which includes a gas-tight casing or shell 2, comprising mated sections 2 and 4 and an interposed spacer ring 5. The sections include cylindrical walls 6 closed at one of their ends by heads I and provided at their opposite ends with radially extending peripheral flanges 8. The ring .5 conforms to the inner diameter of the sections and its outer diameter corresponds to the outer diameter of the flanges 8. The ring is provided with a radially extending outlet port 9, having connection with a discharge duct l2.

preferably formed of extremely light weight, flexible, metallic strips 22 that have one end overlying the ports and their opposite ends secured to the heads l4 and I! by fastening devices, such as screws 2|, whereby the free ends are adapted to flex to and from covering relation with the ports responsive to movement of gaseous fluid therethrough, as later described. The light weight construction of the check valves is important for the reason that'they must have very low inertia, and so that they can open and close quickly responsive to pulsations produced by an alternating current as later described.

The compressor heads carry flexible metallic bellows 22 and 22 that are of cylindrical character and arranged in coaxial sleeved relation with the onset portions of the compressor heads. The

. bellows 22 and 22 include a plurality of accordion I folds 24, and have their inner ends 22 welded or otherwise attached to the outer faces of the compressor heads, as indicated at 22. The opposite ends oi the bellows terminate in laterally extending peripheral flanges 21 which are welded or otherwise secured to the peripheries of dia phragm plates 22 and 29, which close the outer ends of the respective bellows and cooperate with the compressor heads to form compression chambars 22 and 2i. The diaphragms 22 and 22 are provided with axial ports 22 and 22 that are normally closed on the inner sides of the diaphragm.

- by check valves 24' and 25 of the same light Engaged between the flanges 2" and the ring 5 are compressor heads II and 12, each including a circular disk having cylindrical offsets located in the axis of the casing'and extending in the direction of the heads I. The inner ends of the oflsets are open and communicate directly with the space l2 afforded by the thickness of the spacer-ring. The outer ends of the oifsets are closed by integral heads l4 and It, having axial ports i2 and I! that are closed on the inner sides of the heads by check valves l2 and It. The

check valves are of reed-like construction and 55 42, having reduced ends 41 engaged in weight,v flexible construction as the check valves previously described.

The bellows diaphragms are pulsated back and forth in the manner of pistons to draw gaseous fluid through the ports 22 and 22 and to compress the fluid through the ports l8 and I1 upon contraction of the bellows by electrodynamic motors 26 and 31.

The motors 28 and 21 are housed within the outer ends ofthe respective casing sections. Each motor includes a magnetizablejring-like body 22, closely conforming to the inner diameter of the shell sections and which abuts against the inner faces of the respective heads I. -The rings are preferably secured in position by pins 29 extending through suitable openings 40 in the cylindrical walls of the sections and into aligning sockets 4| in the peripheries ofthe rings.

' The rings are provided with cylindrical recesses openings 48 of the rings 38 and which are staked therein as indicated at 49. the pole pieces project from the coils in the directions of the diaphragms 20 and 29. The open sides of the recesses 52 are closed by ring-like disks 50 that are sleeved over the projecting ends of the pole pieces. Secured to the inner faces of the rings 38 are substantially heavy magnetizable rings BI that conform in outer diameter therewith and have central, cylindrical openings of larger diameters than the pole pieces to form annular fields or gaps 52 therebetween. The rings 5i are secured to the ring-like bodies 30, so as to retain the field windings, by fastening devices, such as screws 53, that extend through openings 54 in the ring SI and. into threaded sockets 05 in the rings 38.

Fixed to the outer face of each diaphragm pla te. and perable over the pole pieces, are armature coils 56 and 51 that are contained between cylindrical sleeves 50 and 59, the inner sleeve The opposite ends of being of suitable diameter to move freely over the pole pieces and the outer sleeves to move freely within the rings 5|. The ends of the sleeves are closed by rings 60 and 0| to retain the coil windings therebetween.- The sleeves and rings thus described are formed of non-magnetic, and nonconductlve materials. The inner ends of the outer sleeves are engaged within annular rings 62 having flanges 83 that are riveted or otherwise attached to the outer faces of the diaphragm plates, as indicated at 64. The sleeves are also riveted or otherwise secured to the retaining rings so that they are carried with the diaphragm plates to effect movement thereof as later described. The inner ends of the sleeves and rings are provided with radially extending ports 60,

through which gaseous fluid is delivered for flow through the ports 80 and 33' into the compression chambers of the bellows.

- The terminal ends 00 and 01 for the field coil 43, and 08 and 80 for the field coil 44, extend through channels I0 in the respective rings 50 and connect with binding posts I I--12 and 13-44 that are insulatingly supported in the outer walls of the casing sections, as clearly shown in Fig. 1. The terminal ends 15 and 18 of the moving coil 56, and I1 and 10 for the moving coil bl are con nected by flexible leads i0 with similar binding posts 800I and 0243 respectively.

When the motor and bellows units thus described are installed in their respective casing sections, the sections are secured to the comthat a strong, magnetic fleld is built up across the annular gaps in which the movable coils are located, the movable coils being supplied with alternating current forming electromagnets of changing polarity to set up alternating magnetic field within the constant magnetic fields surrounding the pole pieces. With this arrangement the poles of the coils reverse in accordance with the alternations of the current so that the coils are alternately repulsed and attracted by the pole pieces, setting up a reciprocating movement of the bellows. The winding of the movable coils is such that they move toward each other at the same time causing equal and opposite reactions on the bellows, thereby preventing vibration inciclental to the. reciprocatory movement. As the diaphragms are drawn outwardly from the compressor heads to expand the respective bellows,

gaseous fluid supplied through the ducts 00 and 9| is passed through the ports 02 and 33 and into the interior of the bellows, the increasing pressure in the intake lifting the reed-like check valves 34' and". During this movement of the bellows the check valves I0 and I! are closed. When the current flow is reversed, the polarity of the coils change and they are repulsed to move the diaphragms inwardly toward the compressor heads, trapping the gaseous'fluid within the bellows chamber and forcing it through the ports I0 and I1 and past the reed-like check valves I8 and I9 into the space I3 for discharge under higher pressure through the outlet duct II, thus completing one cycle of operation. It is obvious that a cycle occurs on each alternation of the current flow in the movable coils, so that the bellows continue to pump the gaseous fluid from the ducts 90 and SI and discharge it under higher pressure through the duct III for return to the refrigerating system.

From the foregoing it is obvious that I have provided an electrodynamic compressor that is pressor heads and to the respective sides of the ring 5 by fastening devices, such asbolts 84, extending through aligning openings 00 in the flanges 8, 06 in the compressor heads, and 87 in the ring 5, as shown in Fig. 1. The spaces surrounding the bellows form inlet chambers 00 and 80 that are supplied with gaseous medium through ducts 90 and SI, leading from a source of supply such as a refrigerating-system (not shown). The

binding posts 12 and 14 are connected in series by a conductor 02, while the corresponding binding posts II-I2 are connected by conductors 93 and 94 with a source of direct current supply, for

example, with the filament and plate leads of a fuli wave rectifier 00, which rectifies an alterating current supplied through the secondary windings 96 and 91 of a transformer .00, the windings being arranged so that the pole pieces of the respective motors have reverse polarity. The binding posts BI and 83 of the movable coils are connected by a common conductor 00 and the bindin: posts 80 and 02 are connected byv conductors of simple and inexpensive construction and which may be sealed within a gas-tight case, as shown. It is also obviousthat since there are no parts moving in sliding contact there is no necessi y I for lubrication and no parts subiect to frictional wear. The compressor is also of sturdy construction and'not likely to get out of order due to the simplicity and few working parts.

What I claim and desire to secure by Letters Patent is:-

1. In a device of the character described, walls forming a chamber, a pair of opposed fluid displacing members carried by the walls and dis:

charging into said chamber, a dynamic coil for each displacing member, a non-magnetic support connecting the respective dynamic coils with their displacing members, magnets for establishing magnetic fields in the mne of said dynamic coils, and means simultaneously supplying to said coils an alternating electrical current at commercial frequencies to eflect synchronous movement of the coils to pulsate the-displacing members.

2. In an apparatus of the characterdescribed,

a casing, a pair of spaced heads in the casing having outwardly oilset portion provided with discharge ports, bellows respectively connected,

.said inlet and outlet ports, means supplying a gaseous fluid to the casing, means for conducting the gaseous fluid from the space between said spaced heads, a dynamic coil for each bellows, a non-magnetic support on each diaphragm head for mounting the respective dynamic coils, means in the casing for establishing individual magnetic fields in the-zone of the respective dynamic coils, and means for supplying a fluctuating current to the coils for establishing an alternating polarity in said coils relatively to the magnetic fields for effecting expansion andcontraction of the bellows responsiveto dynamic movement of the coils in the magnetic fields.

3. In an apparatus of the character described, a casing, a pair of spaced heads in the casing having outwardly offset portions provided with discharge ports, bellows respectively connected with the spaced heads in telescoping relation with said offset portions to form compression chambers, diaphragm heads closing the opposite ends of the bellows and having inlet ports into the compression chambers, valves controlling said inlet and outlet ports, means supplying a gaseous fluid to the casing, means for conducting the gaseous fiuid from the space between said spaced heads, a dynamic coil for each bellows, a nonmagnetic support on each diaphragm head for mounting the respective dynamic coils, electromagnets in the casing for establishing individual magnetic fields in the zone of the respective dynamic coils, ,means for supplying a fluctuating current to the coils for establishing an alternating polarity in said coils relatively to the magnetic fields for effecting expansion and con traction of the bellows responsive to dynamic movement of the coils in the magnetic fields, and means supplying a direct current to the electromagnets.

EMMETT F. SARVER. 

